While the scant use among youth may be discouraging for Twitter, the company may not even notice for some time as it is still experiencing growth elsewhere.

Twitter CEO Dick Costolo recently told the Los Angeles Times that the social network has 140 million active users. Costolo said Twitter's growth is coming from users in other countries, particularly those in the Middle East. Saudi Arabia alone saw growth of 3,000% in June, he said.

And as the site grows globally so do the number of tweets sent each day.

“It took three years and two months to send the first 1 billion tweets," he said. "Now 400 million tweets are sent a day. It takes 2½ days to send 1 billion tweets.”